The present invention relates to an open end wrench and, more particularly, to an open end wrench capable of fast driving and having high toughness and a long service life, with the open end wrench including a jaw portion having an increased elastic deforming effect when the jaw portion is subject to a reactive force from a workpiece, avoiding damage to a slider and the jaw portion resulting from failure to withstand the reactive force form the workpiece.
U.S. Pat. No. 4,158,975 and U.S. Publication Nos. 2008/0066585; 2010/0071516; and 2010/0083797 disclose open end wrenches with a limited torque capacity. To provide a ratcheting effect, a pawl or a slider movable relative to a wrench body is provided to hold a workpiece. However, in an operation requiring a high torque, the structure of the pawl or the slider cannot withstand the reactive force from the workpiece and is, thus, apt to break.
As an example, when a user finds the torque is insufficient during operation, a metal tube is coupled to the handle to increase the lever arm for the purposes of proceeding with a high-torque wrenching operation. Nevertheless, the wrench body must be drilled to form a hole, a groove, or the like for installing the movable member, such as a pawl or a slider, resulting in a reduction in the structural strength of the wrench body. Thus, the pawl or the slide is apt to be damaged by the reactive force from the workpiece while wrenching the workpiece.
The open end wrench disclosed in U.S. Publication No. 2010/0083797 includes an evaded slot. As shown in FIG. 5, the evaded slot is formed between the supporting surface (153) and the curved slot (16) and is adapted to receive a corner of the bolt (C) while rotating the bolt (C). However, during a high-torque wrenching operation, the open end wrench is apt to brake or damage at the location where the evaded slot is formed.
Conventional open end wrenches are generally increased in the rigidity for withstanding high-torque operations. However, the open end wrench could instantly break when subject to a force approximating 80-100% of the rigidity while wrenching the workpiece without any warning, leading to injury to the user and having a short service life.
Thus, a need exists for a novel open end wrench that mitigates and/or obviates the above disadvantages.